The departed in 2011

MITCH CERRONE, CHICAGO TRIBUNE

He took his own life last February with a bullet to the heart. It was a gunshot that shook the sport of football. Duerson was depressed for a variety of reasons and suffered from CTE, which was caused by brain-related trauma. Eleven months later, the world still is trying to make sense of what happened.

He took his own life last February with a bullet to the heart. It was a gunshot that shook the sport of football. Duerson was depressed for a variety of reasons and suffered from CTE, which was caused by brain-related trauma. Eleven months later, the world still is trying to make sense of what happened. (MITCH CERRONE, CHICAGO TRIBUNE)

At age 24, the 2008 Olympic marathon champion (and two-time Chicago Marathon champion) was on his way to becoming the greatest marathoner in history. His May 16 death at his home in Kenya under circumstances that remain unclear deprived us of the chance to witness greatness several more times.

At age 24, the 2008 Olympic marathon champion (and two-time Chicago Marathon champion) was on his way to becoming the greatest marathoner in history. His May 16 death at his home in Kenya under circumstances that remain unclear deprived us of the chance to witness greatness several more times. (Jim Prisching, Getty Images)